In the manufacture of electrical rotating apparatus, such as armature coils, a trickle varnish is slowly painted over the completed coils of a stator and is cured on the coil. The principal purpose of the varnish is to prevent the wires that form the coil from moving or flying apart when the coil is rotated or is in a large magnetic field. Since the coils are often operated at elevated temperatures, a suitable varnish for this purpose must have a high bond strength at temperatures of up to about 150.degree. C. In addition, a good trickle varnish should have good electrical properties so that it adds to the insulation of the coil. Because of regulations prohibiting the emission of solvents into the atmosphere, it is also desirable that the varnish be 100% solids and contain no substance that will evaporate into the atmosphere. Of course, to be economically useful, the varnish should also be made of inexpensive materials, should have a low viscosity, and be fast gelling and fast curing, in order to reduce manufacturing costs. Until now it has been very difficult to obtain a varnish which has all of these properties.